You may think that just because alcohol is something that you use in order to keep things clean, you can use this to kill cockroaches. Cockroaches are very complex to kill. The only way that alcohol can kill cockroaches is if you would directly spray it to the nozzle that cockroaches use in order to breathe.
If it stops breathing, then it dies. If you just let the alcohol reach the cockroach and it does not pool around the roach, nothing will happen. If you want to effectively kill the cockroach, you need to use a lot of alcohol and this may not be ideal if you find it wasteful.
Cockroaches are difficult to kill. First, they can move quickly and in different directions if you try to stomp on them or grab a can of spray that you put underneath the sink counter in the bathroom. Cockroaches can live a little while even if their heads are taken off. However, a roach can be killed using rubbing alcohol.
First, put the rubbing alcohol in a container that has a squirt nozzle to it. Then with a long stream, squirt the cockroach. The roach is best squirted straight on because it will cause them to stop breathing. Like many other ways, the roach will suffocate. You can suffocate a roach with other items. However, rubbing alcohol does kill if the stream of alcohol can pool around the roach.